Introduction to the Volume

Abstract

In 1979 meteorologist Jule Charney and colleagues published a globally recognized report on Carbon Dioxide and Climate: A Scientific Assessment (Charney et al. 1979). They finished the report with the conclusions that “our best estimate is that changes in global temperature on the order of 3°C will occur and that these will be accompanied by significant changes in regional climatic patterns” (p. 17). The estimates of the so-called Charney report were based on two, at that time state-of-the art, general circulation models of the atmosphere that carried out numerical studies on the impact of doubling carbon dioxide on the global mean temperature. This measure, called climate sensitivity, was introduced by Charney et al. and were supposed to provide some insight into the ‘vast geophysical experiment’ mankind was about to conduct (Revelle and Suess 1957). A full two decades before the release of the Charney report, Charles D. Keeling had begun measurements of atmospheric carbon dioxide concentration at Mauna Loa Observatory in Hawaii in order “to make sure that man’s ‘vast geophysical experiment’ would be properly monitored and its results analyzed” (Keeling 1978, p. 38). The ‘Keeling Curve’, a time series of annual departures from 1958 on, clearly shows the increased CO₂ concentration in the atmosphere. This curve has become one of the icons of man-induced climate change today. However, this kind of ‘vast geophysical experiment’ should be subject to a digital climate, not to nature. Therefore climate models are indispensable tools for the emerging climate change science. Rooted in simple barotropic models of the atmosphere, first computed by Charney and colleagues on ENIAC in 1950, these models have developed into complex Earth system models—incorporating knowledge from not only meteorology, but also oceanography, hydrology, biology, geochemistry, economy, and other fields. Within the last six decades, climate models have turned from purely meteorological into multidisciplinary objects of Earth science. Similarly, forecasts of changes in air pressure fields based on barotropic models have developed into projections of climate change and its impact on ecology using vast software machineries.